The index rose to 0.4 percent in March after rising an identical 0.4 percent in February and 0.2 percent in January, the Conference Board said.
The index that assigns a base value of 100 to the year 2004 to provide a reference point, rose to 102.8 with three of seven component indexes making positive contributions in the month.
"The U.K. leading economic index increased modestly for the third month in a row, suggesting that the economy will continue to expand slightly over the near term," says Conference Board economist Brian Schaitkin in a statement.
"Improved business confidence along with an expansion of the Funding for Lending Scheme could help boost business investment. However, weak eurozone economic performance and continued austerity measures remain difficult headwinds to overcome," he said.
The Conference Board said the Coincident Index for Britain, which measures current economic activity, was unchanged in March after rising 0.2 percent in February and dropping 0.1 percent in January.
The Coincident Index held at 104.1.